Accessory Soleus: A Case Report of Exertional Compartment and Tarsal Tunnel Syndrome Associated With an Accessory Soleus Muscle.

An accessory soleus muscle is a rare anatomic variant that frequently presents as an asymptomatic soft tissue swelling in the posteromedial ankle. Less frequently, the anomalous muscle can cause pain and swelling with activity. We present the case of a 17-year-old male with exertional compartment syndrome and associated tarsal tunnel syndrome secondary to a very large accessory soleus muscle. After surgical excision, the patient was able to return to full activity with complete resolution of symptoms.